BANGKOK—An investigation is underway in Thailand after the body of a Swiss woman was found Thursday at a secluded spot on the southern island of Phuket. Thai media reported that the woman’s partially clothed body was lying face down in a rock crevice near a waterfall and appeared to have been concealed by a sheet. Personal documents nearby showed she was 57 years old. The circumstances of the death weren’t immediately clear, but Thai Foreign Ministry spokesperson Tanee Sangrat said in a message posted to an online media group that Foreign Minister Don Pramudwinai had contacted the Swiss ambassador to express his condolences “on the murder of a Swiss woman in Phuket.” Tanee said the Phuket governor has promised an immediate investigation and autopsy. The Swiss Department of Foreign Affairs said in an e-mail it was aware of the death of “an alleged Swiss citizen” in Phuket and that the …